Human milk is considered the ‘golden standard’ for infant nutrition. Processing animal milk, for example cow's milk, to more resemble the composition of human milk is known in the art. Such processing is known in the art as ‘humanizing’ animal milk.
The process of humanizing animal milk involves changing the ratio of casein/whey proteins from approximately 80/20 to approximately 40/60, which is the ratio found in human milk.
WO 2011/051557 describes a process for increasing the casein content of whey protein isolate for the preparation of a palatable beverage for athletes and other exercise enthusiasts, comprising the steps of subjecting skim milk to microfiltration (MF) and ultrafiltration (UF).
WO 96/08155 describes a process for treating skim milk for the manufacture of cheese and milk powders, wherein whey proteins are removed from skim milk by microfiltration and ultrafiltration. Volume concentration factors of 20-100 are employed in the UF step. No recombination of the MF retentate and UF permeate is described for the preparation of infant formulae and no attention is given to the concentration of minerals and trace elements such as phosphorus.
U.S. Pat. No. 5,503,865 discloses a process for treating skim milk, comprising microfiltration or ultrafiltration, the permeate of which needs to be demineralised by for example ion exchange and/or electrodialysis in order to make the skim milk product suitable to be used in infant formulae.
WO 2008/127104 discloses the production of whey protein serum comprising residual beta casein by subjecting cow's milk to microfiltration over a membrane with a pore size of 0.3-0.5 micrometer at a temperature between 10 and 20° C., optionally with a further concentration step via ultrafiltration. No specific steps are described to prepare infant formulae.
The process of U.S. Pat. No. 5,169,666 uses even lower temperatures (4° C.) at which the microfiltration over membranes with a pore size of 0.1-0.2 micrometer is performed. At this temperature beta casein dissociates from the casein micelles and ends up in the MF permeate. Apart from being undesirably high in casein, the MF permeate is also too high in ash to be suitable for use in infant formulae. No measures are described to further reduce the ash content.
EP 1133238 describes a process wherein animal milk is subjected to microfiltration through a membrane having a porosity of 0.1-0.2 micrometer, after which the MF permeate is demineralised by electrodialysis. The mineral content of the electrodialyzed MF permeate is very low, and subsequent fortification with minerals and trace elements is required to obtain an infant formula.